Western Red Cedar — Thuja plicata
The classic North American softwood — naturally durable, lightweight, dimensionally stable, and renowned for sauna construction. Class 2 above-ground heartwood from western Canada and the Pacific Northwest. The benchmark species for premium sauna interiors, luxury cladding and architectural softwood applications.
Western Red Cedar products
Premium kiln-dried, clear-grade Canadian Western Red Cedar — the benchmark for luxury sauna construction. Cladding, lining and exterior applications by enquiry.
Technical ReferenceSummary
Western Red Cedar (Thuja plicata) is native to the temperate rainforests of western Canada and the Pacific Northwest United States. Globally specified for cladding, lining, decking, joinery and most famously sauna construction — its combination of natural durability, dimensional stability, low density, and resistance to heat and moisture makes it the world benchmark for luxury sauna interiors.
Heartwood is rated Class 2 — Durable above ground (15–40 years per AS 5604), with Lyctus immunity, termite resistance, and excellent dimensional stability. Density just 350 kg/m³ — exceptionally light for its durability — makes it easy to handle, mill and install. Strength Group SD8 seasoned (S7 unseasoned) — this is a softwood not specified for structural use, but is unmatched for sauna, cladding and interior applications.
Class 2 of 4
Character & Appearance
Heartwood is reddish-brown to deep chocolate — sometimes with darker streaks — and weathers to a soft silvery grey if left untreated. Sapwood is pale yellow to white, narrow, and clearly distinct. Western Red Cedar carries a characteristic resinous fragrance that intensifies in heated conditions — the foundation of the traditional Scandinavian and Canadian sauna experience.
Grain is straight and uniform, with a fine even texture. The wood is light, soft and dimensionally stable — easy to machine, glue, finish and bend. Holds fixings reliably with stainless or hot-dipped galvanised fasteners. The natural oils that confer durability also make it resistant to splitting and warping under heat and moisture.
Species & General Properties
Mechanical & Physical Properties
| Property | Unseasoned | Seasoned |
|---|---|---|
| Density | 490 kg/m³ | 350 kg/m³ |
| Janka hardness | 1.2 kN | 1.6 kN |
| Modulus of rupture (bending) | 35.9 MPa | 51.7 MPa |
| Modulus of elasticity | 6.5 GPa | 7.7 GPa |
| Maximum crushing strength | 19.1 MPa | 31.4 MPa |
| Strength Group | S7 | SD8 |
| Stress Grade (Structural No.1) | F7 | F8 |
| Joint Group | — | JD6 |
| Shrinkage (Total) | Value |
|---|---|
| Tangential shrinkage | 2.30 % |
| Radial shrinkage | 1.10 % |
Recommended Applications
Western Red Cedar is the world benchmark species for sauna construction and a long-standing favourite for premium cladding, lining and architectural softwood work. Its low density, dimensional stability and natural fragrance set it apart from any Australian native softwood alternative.
Specification Notes
- Natural durability ratings apply to heartwood only. Sapwood is not naturally durable.
- Recommended spec wording: "Western Red Cedar (Thuja plicata) heartwood — AS 5604 Class 2 above-ground durability, Strength Group SD8 seasoned, Joint Group JD6 seasoned, F-grade F8 seasoned. Not specified for structural use."
- Sauna applications: WRC is the world standard for sauna walls, ceilings and bench frames. Heat and moisture resistance combined with low thermal conductivity make it comfortable to touch even at sauna operating temperatures.
- Fastener compatibility: Use stainless steel (316 for coastal, 304 inland) or hot-dipped galvanised fasteners. Standard plain steel will react with natural cedar tannins.
- Lyctus: not susceptible. Termite: resistant heartwood.
- Bushfire performance: BAL 12.5 and 19 approved under AS 3959.
- For coastal or UV-exposed applications, oil within 2 weeks of install then 12-monthly maintenance to slow the natural silver-grey weathering.
References
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Premium clear-grade Canadian WRC for sauna, cladding and joinery. Hand-selected, kiln-dried, stocked in Brisbane. Talk to us about profile, length and lead time.